Any way to compile an old version from git?

[Ben Lippmeier]

On 18/05/2011, at 6:31 PM, Ben Lippmeier wrote:

> On 18/05/2011, at 6:17 PM, Erik de Castro Lopo wrote:

>> In what litrle spare time I have I have been working on debugging
>> a problem that only seems to arise on linux-powerpc (bug #5111).
>> 
>> Since I'm time poor and CPU rich, I thought it might be useful to
>> try and use a bisect appraoch to try and find when the bug was
>> introduced. Unfortunately, if I do a git checkout of an old
>> revision (I tried with a commit dated Jan 4th 2011) and try and
>> build it it fails to build because the other source trees grabbed
>> via the sync-all script is not in sync with the main ghc tree.
>> 
>> Does anyone have a way of grabbing a snapshot of the source
>> tree from some arbitrary date?
> 
> I don't think that's possible. I've made tarballs of GHC states in the past, saving them explicitly because rolling-back would be too hard. It would be nice if it was possible though.
> 
> The patch history doesn't provide a working build at every point anyway. People push *bundles* of patches, and the build needs to work after the bundle, but it doesn't need to work after every patch. As we don't record the bundles, the best you could really do is to examine the timestamps of the commit messages in the mailing list, I think.

Though perhaps the buildbot, on completing a successful build, could record the hash of the most recent patch in each of the repos -- if it doesn't already.

Ben.